Coronary Artery Disease (CAD)

What is coronary artery disease (CAD), or heart disease?

CAD is buildup of cholesterol in the arteries of the heart. Sometimes calcium also buids up in the arteries, but this follows the cholesterol. A coronary calcium score will give you an indication how much cholesterol is likely to be in the arteries. A coronary CT scan will take pictures of the heart and indicate how much cholesterol disease is present with a great deal of accuracy for a non-invasive test. A coronary angiogram provides the best images of the lumen of the artery, determines if any significant blockages are present, and is required prior to any invasive treatment.

Coronary artery disease can happen even in the absence of "elevated" cholesterol levels, especially in patients with diabetes or high blood pressure, smokers, and patients with a strong family history. Elevated cholesterol, defined as a total cholesterol greater than 200 mg/dL, is a relative term. People at appropriate weight and activity level who follow a healthy vegetarian diet typically have total cholesterol levels below 150 mg/dL, while the national average is over 200. Good cholesterol, or HDL is very important as well. People with a normal total cholesterol, but low HDL, have an equivalent cardiac risk as people with elevated cholesterol.

Traditional risk factors for CAD are:

High cholesterol
Diabetes
Smoking tobacco
High blood pressure
Family history

Nontraditional CAD risk factors include:

Obesity and inactivity
Stress
Inflammation (arthritis, infections, high CRP)
Chronic infections (Hepatitis, HIV, EBV, CMV, periodontal disease)
Air Pollution
Kidney failure
Others

Where exactly does the disease occur?

CAD involves buildup of cholesterol in the arteries that feed blood to the heart muscle. With blockage of flow, the heart does not receive enough oxygen, especially during exercise or times of stress. There is usually one main artery, called the left main, and three major arteries, called the LAD, circumflex and right coronary artery. There are anatomic variations as well. Most of the cholesterol buildup occurs inside the wall of the artery, and blockage of blood flow is a late finding. Most people have at least some cholesterol deposits in the heart arteries. By the time there is a significant blockage, there is extensive disease throughout the vessel wall, which may not all be visible inside the lumen.

Diagrams of the coronary artery anatomy

How is the blockage treated?

An angiogram will determine the degree of cholesterol buildup and blockage of flow to the heart muscle. Small studies have demonstrated that repairing blockages of 70% or more will reduce the risk of heart attack or death, even in the absence of symptoms such as chest pain, although these conclusions still remain controversial. Treating blockages of 50% or more will often improve symptoms of fatigue, shortness of breath, or chest pressure. Recently, a large study showed treating stable angina patients with stents did not reduce the risk of heart attack or death, and had a modest impact in symptoms. Many patients in the medication arm of this study later had stents placed for worsening symptoms.

The physician performing the angiogram will review the pictures with the patient and family, and determine the best treatment strategy. Blockages of less than 50% are ugenerally treated with medications, as are blockages in small arteries of less than 2mm in diameter. Blockages of 50-60% may be treated with medications, stents, or bypass surgery, depending on patient symptoms, disease location, and physician preference. Blockages of 60-99% are still usually treated with stents or bypass surgery, depending on the number and location of the diseased vessels. Blockages of 100% may be difficult to treat with stents, and may be treated with surgery or medications.